Method push

src/include/common/mpsc_queue.h:46–57

NOTE: It is NOT guaranteed that the result of a push() is accessible to a thread that calls pop() after the push(), because of implementation details. See the body of the function for details.

    // pop() after the push(), because of implementation details. See the body of the function for
    // details.
    void push(T elem) {
        Node* node = new Node(std::move(elem));
        _approxSize.fetch_add(1, std::memory_order_relaxed);
        // ORDERING: must acquire any updates to prev before modifying it, and release our updates
        // to node for other producers.
        Node* prev = tail.exchange(node, std::memory_order_acq_rel);
        // NOTE: If the thread is suspended here, then ALL FUTURE push() calls will be INACCESSIBLE
        // by pop() calls until the next line runs. In order to guarantee that a push() is visible
        // to a thread that calls pop(), ALL push() calls must have completed.
        // ORDERING: must make updates visible to consumers.
        prev->next.store(node, std::memory_order_release);
    }

    // NOTE: It is NOT safe to call pop() from multiple threads without synchronization.
    bool pop(T& elem) {